Hello Eric. Many thanks for developing this app for us!
I access my X18 Mixer via an external router, and the X18 reassigns a new IP address every time I disconnect/reconnect the unit. No biggie for me, as I simply need to assign a last digit to the IP address until I find the mixer.
The app found my external router immediately, though it displayed a default IP address for the mixer and couldn't initially connect. Once I changed the last digit of the IP address to match the mixer, it worked fine.
Very simple attractive layout, with scribble strips and channel names matching up to the mixer's last setup perfectly. Although it displays all 18 channels across a single iPhone 5 screen, I was surprised how manageable it was to work with and didn't find the display to be too tiny at all. Even my sausage fingers had no trouble accessing each slider.
There was one bug I encountered, however, that I'd like to inform you.
Busses cannot be selected on the fly. When I click on the gear icon to select a bus and click on any one, the screen on my iPhone 5 (IOS 10.3.3) goes white. I have to double click my home button to back out of the app, then click on the app again in order for the selected bus's setup to appear.